A flight from Warsaw to Tel Aviv ended with an unscheduled landing in Burgas, Bulgaria, after the aircraft transmitted transponder code 7500, the internationally recognised signal indicating possible unlawful interference on board, including a potential hijacking.

According to Bulgarian public broadcaster BNT, the aircraft involved was an Airbus A320 that entered Bulgarian airspace from the north, over the Danube River. The 7500 signal immediately triggered security procedures, prompting the Bulgarian Air Force to scramble standby MiG-29 fighter jets.

Bulgaria’s Ministry of Defence, as reported by The Sofia Globe, said the aircraft entered Bulgarian airspace at 13:57, while the standby MiG-29 from the Third Air Base at Graf Ignatievo had taken off three minutes earlier. The Bulgarian pilot carried out standard identification, communication and escort procedures, accompanying the aircraft to the Turkish border.

After the aircraft entered Turkish airspace, the escort was taken over by two Turkish F-16 fighter jets. Turkish authorities confirmed that standard international security procedures had been applied after the aircraft transmitted code 7500 while still over Bulgaria.

Further uncertainty was caused by reports in Israeli media that contact with the aircraft had briefly been lost over the Mediterranean Sea. The Israeli Air Force also scrambled fighter jets, but contact was soon restored. According to The Times of Israel, the Israel Defense Forces later found no indication of a security incident.

The aircraft then changed course and returned towards Bulgaria, where Bulgarian fighter jets intercepted it again and escorted it to Burgas Airport. It landed safely there, and according to available information, there were no injuries among passengers or crew members.

Although the initial activation of code 7500 indicated a potentially serious security threat, later information suggests it was a false alarm. Some sources mention a possible technical issue with the transponder, while other reports point to the possibility of an incorrectly entered code. A final official explanation for the cause of the incident has not yet been published.

Transponder code 7500 is one of three universal emergency codes used in aviation. Code 7600 indicates a loss of radio communication, while 7700 is used for a general emergency. Unlike other operational irregularities, code 7500 is immediately treated as a possible security incident, requiring civil and military authorities to launch established procedures without waiting for additional confirmation.

The case showed that even a false alarm in air traffic must be treated as a real threat until proven otherwise. Bulgaria’s Ministry of Defence described the airspace security mission as successfully completed, highlighting the rapid response of standby forces and coordination with the Turkish Air Force.